Along with increase of a volume of data handled in a computer and the like, data transmission is being changed from data transmission using an electric signal to data transmission using a optical signal. For example, also among transceivers or other various kinds of devices and equipment and the like, there are ones which send and receive data (signals) to/from outside using a optical signal. When data transmission is performed using a optical signal, there is used a technology of silicon photonics with which an optical circuit to process a optical signal is formed as a silicon chip (hereinafter, it is referred to as an optical module accordingly) using a method to mount optical elements on a silicon substrate.
In such optical module, an optical waveguide such as an optical fiber needs to be connected to perform data transmission with outside. As a connecting structure between such optical module and an optical fiber, there is disclosed in non-patent literature 1 a structure, in which an optical connector made by uniting a 45-degrees mirror and an optical fiber is connected to a surface of an optical module having a lens installed on an optical element of a surface light emitting/receiving type.
In non-patent literature 2, as an optical connecting structure in which an optical waveguide having a silicon-based material such as silicon and silicon nitride as a waveguide core is connected to an optical module in a vertical direction, there is disclosed a structure in which a diffraction grating is formed in the side of the optical waveguide, and, in addition, an optical fiber is connected with the optical module to tilt about 10 degrees in order to reduce light which returns toward the opposite direction of the optical waveguide.
In non-patent literature 3, there is also disclosed a structure in which identically structured diffraction gratings having optic axes after conversion inclining from the vertical direction are connected to oppose each other and their optic axes being aligned.